The invention is related to to an optical wand for automatic character recognition including a scanner unit designed to be manually movable along a line of print of a data carrier in order to recognize optical characters. The hand held optical reader includes a light source for illuminating a scanning window, and a sensor device for sensing the area of the data carrier currently appearing in the scanning window.
Such sensing devices are utilized with automatic character recognition in order to convert visually readable characters imprinted on a data carrier, i.e. a voucher, a letter or a label directly into a format which can be automatically analyzed and processed. The string of information corresponding to recognized characters is usually furnished to a data processing system or a peripheral unit such as a printer for further processing. By means of an example, U.S. Pat. No. 4,250,488 discloses such an optical device for automatic character recognition which is designed for reading standardized alpha numeric optical characters, such device is usually designated as optical character recognition (OCR) reader.
A different group of automatic recognition devices incorporates devices designed for recognizing coded data imprinted on labels. The coded information is very often represented by so called bar code marks and corresponding reading devices are commercially available, one example is the Ruby Wand Light Pen, model 1240 manufactured and sold by Intermec, Lynnwood, Wa. 98036.
Automatic reading devices designed for recognizing bar code marks have a structure which is quite different from above mentioned devices suitable for optical character recognition. This is quite understandable in view of the totally different appearance of the printed information. OCR readers are designed to sense an area appearing in the scanning window of the reader point-to-point and in parallel thus enabling to reconstruct segments or at least elements of a character. Bar code readers, on the contrary, are much less complicated. A single sensing device associated with an appropriate light source scans the series of bar codes and interprets the apperance of black and white elements in dependence upon a predetermined threshold and derives therefrom a pulse train which is supplied to an evaluation unit.
Bar codes and OCR fonts are commercially utilized in various areas of business and are preferably utilized for making different groups of goods. OCR fonts are very often applied to checks, labels of dresses and a variety of technical articles whereas the bar code marking finds its main application for identifying packaged food. It is conceivable that some businesses, such as department stores sell goods belonging to either one of these two groups. It is therefore necessary to provide for both types of reading devices. This approach means some inconvenience for the organization of sales in such departments stores; it is inefficient and especially impractical for operators such as cashiers to work with different wands for different groups of labels.
U.S. Patent. 3,410,991 discloses a reading device for a data carrier bearing simultaneously a line of visually readable characters and associated therewith corresponding bar code marks imprinted below the respective optical characters. The known reading device includes scanner units designed for sensing the characters and the associated bar code marks simultaneously at several horizontal levels in order to achieve a high scanning immunity in view of tolerances of vertical misalignment of the scanner. The known reading device, however, is not designed for recognizing OCR fonts and bar code marks alternatively.
European Patent Application No. 0,062,777 discloses a combined OCR and bar code reader utilizing a single area array for sensing OCR fonts or bar codes. In other words, the sensor array designed for sensing OCR fonts is also utilized for sensing bar code marks and measures have to be taken in the evaluation unit to distinguish between signal information associated with an OCR font and a bar code, respectively. This kind of a combinative use of a single sensing device for both groups of markings by means of a common sensor array seems to make efficient use of a reading device for different purposes but has some disadvantages. The general difference between recognizing OCR fonts and bar code marks, has been outlined above; it is therefore conceivable that a device utilized for reading both types of markings cannot be as exactly adjusted to all requirements as would be desirable for conditions which are contradictory for reading optical characters and bar code marks, respectively. Furthermore, in case of a failure of the sensor device the entire reader will be out of order.